1. Field of the Invention
The present invention relates generally to the manufacture of chewing gums containing active ingredients and, more specifically, to a method for manufacture of such chewing gums that preserves the efficacy of the active ingredient(s).
2. Description of the Background
The conventional methods of producing compressible chewing gums entail freezing the gum base and then grinding to obtain a particulate material, mixing the particulate material with other materials (usually in particulate form), then pressing the compressible chewing gum mixture into tablets.
For example, U.S. Pat. No. 4,370,350 to Fisher et al. (Wrigley) issued Jan. 25, 1983 shows a method for the manufacture of chewing gum in which the viscosity of the gum base is first reduced by heating. A bulking agent is then added to the gum base while mixing. The mixture is cooled during mixing to form granules. More bulking agent is added to form layers around the granules, and there is no active ingredient nor any grinding or tableting.
For example, U.S. Pat. No. 7,101,579 to Athanikar et al. (Deseret Labs) issued Sep. 5, 2006 shows a chewing gum composition containing an active ingredient. The gum base is cooled to a temperature at which the composition is brittle, ground, mixed with the active ingredient as desired, and formed into a tablet.
U.S. Pat. No. 5,711,961 to Reiner et al. (APR Applied Pharma) issued Jan. 27, 1998 discloses a pharmaceutical chewing gum composition in tablet form made by freezing, grinding the gum in a mill, and granulating the ground gum in a fluid bed. Thereafter, a medicinal active agent is mixed with the granulate, and the granulates are compressed into tablets. This patent is provided for general interest.
U.S. Pat. No. 4,975,270 to Kehoe (Nabisco) issued 4 Dec. 1990 shows a medicament-active chewing gum made by freezing and grinding into a particle. Note that the gum and the active ingredient are mixed together while heating, and then the mixture is frozen and ground into particles.
U.S. Pat. No. 6,582,738 to Gubler (Deseret Laboratories) issued Jun. 24, 2003 shows a process for preparing chewing gum containing a nutritional supplement that includes cooling and grinding the cooled, brittle gum composition to form a chewing gum powder, mixing with an active nutritional supplement, granulating, and then compressing the granules to form chewing gum tablets. The chewing gum composition is cooled to a temperature at which the gum composition is brittle.
Alternatively it is known to mix a powder sweetener into a molten gum base while subjecting the mixture to shear (i.e., through the mixing force) and cooling. This technique causes the grinding as the mixture becomes more rigid due to cooling and the addition of the dry sweetener.
U.S. Pat. No. 4,753,805 to Cherukuri et al. (Warner-Lambert) issued Jun. 28, 1988 shows a tabletted chewing gum composition and method of preparation in which a gum base is mixed with a sweetener, and the mixture is ground with an abrasive grinding aid (alkali metal phosphates, alkaline earth metal phosphates, maltodextrins).
U.S. Pat. No. 7,208,186 (SPI Pharma, Inc.) to Norman et al. issued Apr. 24, 2007 shows a chewing gum formulation with an active ingredient. The gum base, granulating agent and a processing aid are mixed until in particulate form. The temperature in the mixer is then increased to a temperature which is sufficient to melt at least the surface of the gum base particles and the contents of the mixer are mixed for several minutes at this temperature to obtain a uniform mixture of the gum base, the granulating agent and the processing aid in particulate form particles inside the mixer. Next, the active ingredient is added to the particles and most or all of the active ingredient is loosely bound to the outer surfaces of the particles. The particles are tableted. There is no cooling necessary to make the chewing gum formulation friable.
U.S. Pat. No. 7,351,438 to Sozzi et al. (Gum Base Co., SPA) issued Apr. 1, 2008 shows a method of preparing chewing gum in tablet form by direct compression of the chewing gum formulation in powder form. The chewing gum in powder form is produced by a method which comprises the following steps:
a) mixing of a soft basic gum with at least one sweetener and, optionally, at least one other typical chewing-gum ingredient, at a temperature of between 35 and 75° C.,
b) cooling of the mixture thus obtained to a temperature of between 0 and −40° C. and preferably between −10 and −40° C.,
c) grinding and subsequent screening of the mixture thus obtained to a particle size of less than 10 mesh,
d) optional mixing of the powder thus obtained with at least one anti-agglutination agent,
e) optional compression of the mixture thus obtained.
U.S. Pat. No. 5,866,179 to Testa (Avant-Garde Technologies) issued Feb. 2, 1999 shows a medicated chewing gum and a process for preparation thereof in which the active agent is mixed with a granulated gum base under controlled temperature and humidity and the blended components are cold-pressed to produce a final gum product. The gum base is prepared by cooling natural gum to −10 degree C., then grinding it. It is noted that the elevated temperatures used in the melt can adversely affect the chemical stability of the therapeutic agent.
Neither prior method is optimal for chewing gums with active ingredients since heating and/or cooling can erode the effectiveness of the active. The proposed process avoids this by initially heating a gum base to slightly elevated internally measured temperature between 140-160 deg. F. in ovens, mixing with the active as it cools to produce a particulate mixture, grinding into compressible powder, then forming into tablets. The temperature of the gum base exceeds that of the mixer when first introduced, but as mixing continues it cools and mixes into a particulate form=inside the mixer. Next, the particulate is ground into compressible powder at room temperature, mixed at room temperature with excipients, and tableted. This avoids heating/cooling of the active and preserves its efficacy.